Conventionally, for example, the air cooler (fin tube type heat exchanger) according to Patent Document 1 consists of a large number of plate-shaped fins that are arranged in parallel at predetermined intervals and between which an airflow flows and heat transfer pipes that are perpendicularly inserted into the plate-shaped fins and in which a fluid flows. In the air cooler according to Patent Document 1, in order to improve the heat transfer coefficient by reducing the dead water areas that are caused in airflow backward areas with respect to the heat transfer pipes, the pitch L1 between heat transfer pipes in the airflow direction with respect to the outer diameter D of the heat transfer pipe (3 mm≤D≤7.5 mm) is set at 1.2D≤L1≤1.8D and the pitch L2 between heat transfer pipes in the direction orthogonal to the airflow with respect to the outer diameter D of the heat transfer pipe is set at 2.6D≤L2≤3.5D.